Plotting a digital polymer chain.

I got the instructions from my professor and have no idea how to complete the code. The A beads should be red and the B beads should be blue.

1) Create two empty 30 x 2 matrices; one matrix for A beads, the other for B beads.

2) Open a for loop from index i=1:30

3) Calculate a random number

4) If the random number is <=0.5, then for the A matrix, change the i,1 element to the current index in the for loop, and the i,2 element to a value of 1.

If the random number is >0.5, then for the B matrix, change the i,1 element to the current index in the for loop, and the i,2 element to a value of 1.

5) Repeat steps 3 and 4 all the way up to i = 30

6) Close the for loop

7) Remove all the zero rows from the A and B matrices

8) Plot the beads

[darova]

Please show your attempts

Answer 1

[Sydney Carrow]

I don't have any attempts because I do not know how to do any of it. I can't figure out how to make empty matrices. Once creating the loop, I do not not how to do what he said.

[darova]

You are in a terrible situation. What can i do for you?

[Sydney Carrow]

1) show how to create empty matrices as he described and 2) show how to make i,1 change in A

[darova]

Here you go

A = zeros(30,2);
B = zeros(30,2);
for i = 1:30
    num = rand;
    if num < 0.5
        A(i,1) = num;
    end
end

[Sydney Carrow]

How do I make A(i,1) to the current index in the loop?

[darova]

Current index is "i"

[Sydney Carrow]

This is the code I have created. Now though, the index isn't transfering to A or B as the current index when needed. What can I do?

%chain 1
A=zeros(30,2);
B=zeros(30,2);
for i=1:30
    if A(i,1)==i || rand<=0.5
        A(i,2)=1;
        A(i,1)=i;
    else 
        B(i,1)=i;
        B(i,2)=1;
    if B(i,1)==i || rand<=0.5
       A(i,1)=i;
       A(i,2)=1;
    else
        B(i,1)=i;
        B(i,2)=1;
    end
    end
end
%Deletes all zeros in A
TestForZero = A(:,1) == 0;
A(TestForZero, :) = []

%Deletes all zeros in B
TestForZero = B(:,1) == 0;
B(TestForZero, :) = []

%graphs

hold on
plot(A(:,1),A(:,2),'o','MarkerFaceColor',"red",'MarkerSize',15)
plot(B(:,1),B(:,2),'o','MarkerFaceColor',"blue",'MarkerSize',15)
title("Digital Copolymerchain 4")
axis off
hold off



%Deletes all zeros in A
TestForZero = A(:,1) == 0;
A(TestForZero, :) = []

%Deletes all zeros in B
TestForZero = B(:,1) == 0;
B(TestForZero, :) = []

%graphs
hold on
plot(A(:,1),A(:,2),'o','MarkerFaceColor',"red",'MarkerSize',15)
plot(B(:,1),B(:,2),'o','MarkerFaceColor',"blue",'MarkerSize',15)
title('Digital Colymerchain 1')
axis off
hold off

[darova]

Here are some corrections

You don't need to check A(i,1)==i part

if A(i,1)==i || rand<=0.5

You don't need red square part (it's the same as above)